Structural transformations in graphite induced by magneto-mechanical-milling in hydrogen atmosphere

Smolira, A.; Szymańska, Magdalena; Jartych, E.; Całka, A.; Michalak, Leszek

doi:10.1016/j.jallcom.2005.04.154

Cited by 13 publications

(6 citation statements)

References 21 publications

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“…Hydrogen is incorporated into the regions between the graphene sheets, in accordance with theoretical predictions of [1] and result in increases in sheet separations and a range of different c-axis lattice parameters. In the case of the impact milled sample, milling in hydrogen results in rapid destruction of the graphite sheets and formation of a significantly higher proportion of CnHx type molecules, in accord with previously published time-of-flight mass spectroscopy and Mossbauer results for these materials [6]. XRD peaks which may loosely be associated with a-axis fragments compounded with hydrogen appear and sharpen (Fig.…”

supporting

confidence: 89%

“…One of the reasons for such large discrepancies is that there is insufficient control on milling conditions and milling energy during in a hydrogen atmosphere. Too high a milling energy leads to destruction of the graphite layer structure and formation of CnHx molecules [6]. These molecules have high hydrogen storage capacity; however, decomposition requires annealing to temperatures above 600ºC, which renders carbon in this form unattractive for practical applications.…”

Section: Introductionmentioning

confidence: 99%

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Dependence of Structural Evolution an Hydrogen Storage Mechanism on Milling Parameters during controlled Reactive Milling of Graphite in Hydrogen

Całka

Wexler

Fenwick

2007

SSP

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Graphite was mechano-chemically processed in hydrogen using controlled reactive ball milling (CRBM). As-milled and heat treated products were characterised using techniques of combustion analysis, X-ray diffractometry (XRD), selected area electron diffracton (SAED) and high resolution transmission electron microscopy (HRTEM). Both the mechanisms of hydrogen uptake and of hydrogen evolution during subsequent heat treatment were found to be dependent on the mode of milling. Samples milled under a ball-particle impact mode absorbed more hydrogen (2.7wt%) than the samples milled under shearing mode, but the fraction of hydrogen released during subsequent low temperature heat treatment (220-500ºC) was significantly less than for the samples milled under shear. XRD of the shear milled product showed increased, but varying c-axis lattice parameters while XRD of the impact milled product showed complete loss of (002) graphite and formation of peaks which could be associated with CnHx species. Low temperature heat treatment of the shear milled product resulted in significant disorder in the graphite structure, characterised by a loss of diffraction peak contrast and high background scattering in both XRD and selected area electron diffraction patterns. In contrast there was little change in XRD patterns from impact milled samples during low temperature heat treatment. For the shear milled samples which were heat treated for short times there was also an associated loss of contrast from graphene layers in HRTEM images, however, HRTEM contrast from samples shear milled and heat treated for longer times showed an increased fraction of graphene sheets in the product.It was concluded that hydrogen uptake under impact mode milling was predominately via an irreversible mechanism involving destruction of graphene sheets and reaction to from product including CnHx -type molecules. However, hydrogen uptake under shearing mode milling occurred via a partially reversible mechanism involving absorption between graphite layers and expansion of the graphite inter-sheet spacing.

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supporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Dependence of Structural Evolution an Hydrogen Storage Mechanism on Milling Parameters during controlled Reactive Milling of Graphite in Hydrogen

Całka

Wexler

Fenwick

2007

SSP

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“…If milling of graphite was performed under H 2 atmosphere, amorphization occurred 68 obviously by saturation of the fresh reactive borders with hydrogen (13). Planetary ball milling (room temperature, 80 and 120 h) of graphite with hematite (a-Fe 2 O 3 ) gave solid-state reduction to magnetite (Fe 3 O 4 ) and wustite (FeO) (14).…”

Section: Milling Of Layered Structuresmentioning

confidence: 99%

Mechanochemistry: the varied applications of mechanical bond-breaking

2009

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“…In most of the previous reports, it is clearly indicated from the XRD patterns that the graphitic peak intensity of the carbon materials was signicantly decreased with the elongated milling time. 2,[12][13][14][15] Besides, measured by Raman spectroscopy, the defect density was largely increased in graphite powder during ball-milling. [16][17][18] Correlated to this result, Huang directly observed the introduced defects such as grain boundaries and curves by HRTEM.…”

Section: Introductionmentioning

confidence: 99%

Control of graphitization degree and defects of carbon blacks through ball-milling

Zhang

Cui

et al. 2014

RSC Adv.

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Structural transformations in graphite induced by magneto-mechanical-milling in hydrogen atmosphere

Cited by 13 publications

References 21 publications

Dependence of Structural Evolution an Hydrogen Storage Mechanism on Milling Parameters during controlled Reactive Milling of Graphite in Hydrogen

Dependence of Structural Evolution an Hydrogen Storage Mechanism on Milling Parameters during controlled Reactive Milling of Graphite in Hydrogen

Mechanochemistry: the varied applications of mechanical bond-breaking

Control of graphitization degree and defects of carbon blacks through ball-milling

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